Zhang A, Nicholson R A
Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1994 Jul;108(3):307-10.
The dihydropyrazole RH-3421 inhibits veratridine- and K(+)-induced rises in synaptosomal free Ca2+ with IC50s of 0.2 and 1 microM, respectively. The K(+)-induced rise in free synaptosomal Ca2+, which requires external Ca2+, is also blocked by RH-3421 in the presence of tetrodotoxin. The K(+)-stimulated 45Ca2+ uptake by synaptosomes is unaffected by tetrodotoxin, blocked by cobalt ions and inhibited by RH-3421 both alone (IC50 = 11 microM) and in the presence of tetrodotoxin. RH-3421 does not influence the level of free Ca2+ or basal 45Ca2+ uptake in non-depolarized synaptosomes. The results suggest RH-3421 inhibits voltage-sensitive calcium channels in nerve endings.
二氢吡唑RH - 3421抑制藜芦碱和钾离子诱导的突触体游离钙离子升高，其半数抑制浓度（IC50）分别为0.2和1微摩尔。钾离子诱导的突触体游离钙离子升高需要细胞外钙离子，在存在河豚毒素的情况下，也被RH - 3421阻断。河豚毒素不影响钾离子刺激的突触体对45钙离子的摄取，钴离子可阻断该摄取，RH - 3421单独（IC50 = 11微摩尔）以及在存在河豚毒素的情况下均可抑制该摄取。RH - 3421不影响非去极化突触体中游离钙离子水平或基础45钙离子摄取。结果表明RH - 3421抑制神经末梢中的电压敏感性钙通道。
